1. Field of the Invention
This invention relates to a method for on-site execution of a quick hardening cement composition, and more particularly relates to a quick hardening agent for cement which is to be admixed with a separately prepared cement paste, mortar or concrete immediately before the actual on site execution therewith.
2. Description of the Prior Art
Quick hardening cements such as a cement containing a mixture of alumina cement and gypsum and Jet Cement (trade name of Onoda Cement Co., and Sumitomo Cement Co.) are known.
Although these quick hardening cements have the advantage of developing strength within a short period of time, they are defective in that they tend to set and harden during the transport thereof since the setting time thereof is short.
In order to overcome such a defect, therefore, a setting retarder such as an organic acid is generally added and the composition is cast. However, the composition is still defective in that not only a great amount of retarder is necessary but also the setting time is determined before casting, resulting in a limitation of the execution of the cement in accordance with the determined setting time, and further, the setting time cannot freely be controlled while casting.
In addition, since the setting time changes depending upon the kind and brand of cement and upon other factors such as temperature, moisture, amount mixed, mixing time, etc., generally cements do not set and harden in a previously determined period of time, and therefore it is extremely difficult to appropriately control the setting time.